1. Field of the Invention
The invention relates to an aiming device for sport rifles comprising a sighting ring of variable diameter.
2. Description of the Prior Art
The sighting ring of this type of aiming device includes an opening formed by elastic metal lamellas arranged closely adjacent each other within a tubular housing. Together they form a hollow cylinder centrally disposed around the line of sight of the aiming device. At their free ends, the lamellas extend ramp-like outwardly and have radially inwardly projecting fingers. A sliding control disc is disposed around the lamellas and is axially movable along the ramp-like section of the lamellas for forcing the lamellas inwardly adjusting the size of the opening formed by the lamellas.
When aiming with such an aiming device the target area should be seemingly surrounded by the sighting ring. In view of changing distance and different lighting conditions as well as varying dispositions of the rifleman, however, such result can be achieved only if the inner diameter of the sighting ring can be adjusted for the various conditions.
An aiming device of this type known in the art has a sighting ring consisting essentially of a hollow cylinder provided with axial slots to form lamellas which are ramp-like bent outwardly with radially inwardly extending end portions which surround the line of sight. An axially movable sleeve surrounds the hollow cylinder and is axially movable onto the ramp portion of the lamellas thereby variably compressing the lamellas for changing the diameter of the sighting ring formed by the lamellas. The hollow cylinder and the movable sleeve are supported in the housing by means of cross-bars.
A disadvantage of this kind of aiming device is the fact that a large part of the target area is covered by the cross-bars and also by the annular sighting ring itself. It is to be considered that the outside diameter of the cylinder and sleeve assembly will not change even when the inner diameter of the sighting ring is reduced; this results only in greater radial thickness of the sighting ring by reduction of the inner diameter. Many rifle sportsmen are also distracted by the radial bars which are irritating if the target area contains a cross-bar.
Desirably therefore the annular structure forming the sighting ring should remain relatively narrow independently of the size of its opening and the sighting ring support should not be distractive in any manner.